Tack giving a white mouse to Yum Yum before confronting Zig Zag and the war machine.
For that matter, Tack feeding a group of mice while imprisoned.
Specifically, he tried to feed the white mouse a few scraps of bread, but a bunch of black mice ate them, so he gave the white mouse the whole loaf of bread.
Tack and Princess Yum-Yum make hearts for each other. To be specific, Tack shows off some of his cobbler skills by making a heart shape out of Yum-Yum's shoe strings. She in turn does the same by, albeit subconsciously, with her flowers. The two blush and it's adorable.
Princess Yum-Yum saving Tack from Zig Zag's unjust wrath by deliberating breaking one of her shoes.
Meta-example; while Williams' masterpiece will always technically remain unfinished, he said as of 2013, he has made peace with the films sordid history, and theatrically screened his own directors cut of the film in late 2013, which he says he's satisfied with. And after that, he said he's working on another animated feature!